Effects Of Cyclohexane Research Articles

Isomerization of n-Heptane on Platinum-Zeolite Catalysts in the Presence of Cyclohexane and Benzene

Effect of cyclohexane and benzene on the isomerization of n-heptane on Pt/BEA-Al2O3 and Pt/MORAl2O3 catalysts was studied. In the presence of catalysts with platinum deposited from a [Pt(NH3)4]Cl2 solution, cyclohexane and benzene inhibit the conversion of n-heptane. At the same time, the presence of cycloalkanes and aromatic hydrocarbons leads to an increase in the isomerization selectivity due to the suppression of side reactions of hydrocracking. Samples based on the BEA zeolite were found to be more active as compared with similar samples based on mordenite.

Effects of Cyclohexane- Monoxime and Dioxime on the Electrodeposition of Cobalt

Electrodeposition of cobalt was studied in presence of two additives, cyclohexane oxime (CHO) and cyclohexane dioxime (CHD), which differ by one oxime group. Cyclic voltammetry (CV), potentiostatic deposition with pulsed rotation rates, and galvanostatic deposition with injections of additives were carried out to understand the formation and breakdown of intermediate species that suppress cobalt electrodeposition. While strong and fast suppression was observed for CHD on cobalt deposition, the suppression effect of CHO was much less pronounced. A negative differential resistance in CV was observed for CHD due to a breakdown of suppression, which was related to the reduction of absorbed Co-CHD chelate species. A critical rotation rate was defined for CHD as the minimum rotation required to enable a fully suppressed deposition state. An inversely proportional relation between additive concentration and the square root of critical rotation rate demonstrated an equilibrium between the diffusion of the intermediate in solution and the consumption of intermediate by incorporation into deposit. While a pair of adjacent oxime groups was necessary for a strong fast suppression effect, bulkier molecular structures and stronger chelating resulted in stronger suppression.

Cyclohexane, a Potential Drug of Abuse with Pernicious Effects on the Brain.

Cyclohexane is a volatile solvent used as a harmless substitute for dangerous organic solvents in several products, such as paint thinners, gasoline and adhesives. Many of these products are used as drugs of abuse and can severely damage neural tissue and impair neurological functions. However, there is very little information on the effects of cyclohexane on the brain. In humans, cyclohexane produces headaches, sleepiness, dizziness, limb weakness, motor changes, and verbal memory impairment. Recent studies in mice have demonstrated behavioral alterations, reactive gliosis, microglial reactivity, and oxidative stress in the brains of cyclohexane-exposed animals. This indicates that cyclohexane may represent a potential problem for public health. Therefore, studies are needed to clarify the neurobiological effects of this volatile compound, including the cellular and molecular mechanisms of neurotoxicity, and to minimize the human health risk posed by the intentional or accidental inhalation of this potential drug of abuse.

Effect of cyclohexane as hydrogen-donor in ultradispersed catalytic upgrading of heavy oil

The incorporation of catalysts to enhance downhole upgrading in the Toe-to-Heel Air Injection (THAI) process is limited by deactivation due to coking arising from the cracking of heavy oil. This study aims to reduce the catalyst deactivation problems that can occur with upgrading of heavy oils. Ultradispersed catalyst particles could potentially replace pelleted catalysts which may be difficult to regenerate once deactivated during the THAI operation. The dispersed particles could potentially be applied once through, down-hole for in situ upgrading of heavy oil. The catalyst studied was finely crushed pelleted Ni–Mo/Al2O3 catalyst (2.4μm). The product distribution of liquid, coke and gas may be influenced by the presence of a suitable hydrogen source which promotes hydroconversion reactions rather than simple cracking. In order to improve liquid yield whilst suppressing coke formation, the effect of cyclohexane as hydrogen-donor solvent was studied in a stirred batch reactor (100mL) at temperature 425°C, initial pressure 17.5bar, agitation 500rpm, and a short reaction time of 10min. The use of cyclohexane was evaluated against that of hydrogen gas. The reaction under hydrogen atmosphere significantly reduced coke yield by 41.3% compared with a nitrogen environment under the same conditions. Also, the coke decreased by 6.2–45.4% as the cyclohexane:oil ratio increased from 0.01 to 0.08 (g·g−1) relative to 4.67wt.% of coke observed without added cyclohexane in ultradispersed catalytic upgrading under nitrogen environment. As the cyclohexane:oil ratio increases, the produced oil API gravity and middle distillate fractions (200–343°C) increase whilst the viscosity decreases. An estimated 0.073 CH:oil ratio was found to suppress coke formation in a similar manner to upgrading under hydrogen atmosphere at the same conditions.

Two mesoporous cellular foams materials and their adsorption properties to brominated flame retardants

Two novel mesoporous cellular foams (MCFs) materials with well-defined large and aerogel-like mesostructure were successfully synthesized using tetraethyl orthosilicate as silica source, cyclohexane (CHE) as a swelling agent and triblock copolymer Pluronic P123 and F68 as a template, respectively. The effect of CHE on the expansion of the framework were characterized in detailed by small-angle X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption–desorption. The results showed that CHE was an effective swelling agent on the pore size of MCFs. All as-prepared materials were employed as the adsorbent to brominated flame retardants (BFRs) from environmental water samples. The adsorption study indicated the new materials exhibited superior adsorption capacity, the removal efficiencies of MCF-1-1.5 for seven BFRs reached 81.4–95.2 % in industrial wastewater. The recoveries of method were in the range of 86.3–105.7 % for Xiaoqing River sample and 74.6–114.6 % for chemical plant wastewater sample.

Nucleation of Nanosized Particles (3–100 nm) From Ozone and D-Limonene Reaction

O-29A6-5 Background/Aims: Indoor aerosol particles have been shown to contribute to building occupants' health issues, such as asthma or airway irritation. Currently, a considerable effort has been devoted to understand how health effects associated with aerosol exposure, especially with nano-sized particles. Nevertheless, until recently, there was little information regarding freshly nucleated particles with diameters less than 10 nm due to instrumentation limitation. Methods: Taking advantage of the latest Scanning Mobility Particle Sizer (SMPS) technology (Model 3936, TSI), which provides real-time particle number and size distribution in the range from 3 to 100 nm, this study characterizes the chemistry of D-limonene reacting with ozone as a source of indoor nucleated particles. A series of experiments were conducted in a 4-L glass chamber with various reactant concentrations (2–4 ppbv for Limonene and 3–20 ppbv for ozone). The study also looked at the effects of cyclohexane, used to suppress the influence of OH radicals produced from limonene and ozone reaction, on particle size. Results: The study results show a significant effect of reactant levels on particle mass and size. Higher ozone concentration led to an increase in particle number. However, higher limonene levels led to a considerable increase in mass while particle number remained the same. One possible reason for that effect is excess limonene partitioning on to newly formed particles. In addition, more small new particles were formed with the presence of cyclohexane. The formation of nano-sized particles as low as 4.0 nm was observed with the mode growth rate of 10 to 15 nm per 2.5-minute scan during the first 10 to 15 min after limonene was introduced. Conclusion: The experimental results indicate that at lower levels of limonene and ozone, even smaller particles would be formed with a higher chance of nucleation (3 to −0 nm).

Fluorocarbon and hydrocarbon end groups: effects on mesomorphism and physical properties of smectic liquid crystals

In this article we examine the effects of cyclohexane and perfluorocyclohexane being used as bulky end groups on the mesomorphism of classical smectic liquid crystal mesogens. The mesogen that is used in this work is typical of the MHPOBC family of materials. The mesophase behaviour is investigated and miscibility studies are carried out. Electro-optical evaluation of the materials is investigated to show the effect of the terminal group on physical properties such as spontaneous polarisation and tilt angle.

On the importance of vibrational contributions to small-angle optical rotation: Fluoro-oxirane in gas phase and solution

The specific optical rotation of (S)-fluoro-oxirane in gas phase and solution is predicted using time-dependent density functional theory (B3LYP functional) and coupled cluster linear response theory. Upon vibrational averaging, the coupled cluster singles and doubles model predicts the gas phase specific optical rotation to be 8.1 degrees (dm g/cm(3))(-1) at 355 nm at room temperature. This is an order of magnitude smaller than the B3LYP result of 68.4 degrees (dm g/cm(3))(-1). The main source of this discrepancy is the electronic contribution at the equilibrium geometry. The effects of cyclohexane and acetonitrile solvents are calculated for both the electronic and vibrational contributions with the B3LYP functional. The specific optical rotation is estimated to change significantly depending on the polarity of the solvent, increasing in cyclohexane and decreasing in acetonitrile.

ACUTE INHALATION EXPOSURE TO CYCLOHEXANE AND SCHEDULE-CONTROLLED OPERANT PERFORMANCE IN RATS: COMPARISON TO D-AMPHETAMINE AND CHLORPROMAZINE

Adult male rats pressed a lever on a multiple fixed ratio-fixed interval (FR20-FI120 sec) schedule of food presentation, and after attaining a stable baseline subjects received an acute inhalation exposure to cyclohexane vapor (0 ppm, 500 ppm, 2000 ppm, or 7000 ppm) for 6 hr. During the operant session that began 30 min after termination of exposure, FR running rate for the 7000 ppm group decreased 11% relative to performance on the previous day. FR post-reinforcement pause duration and the rate and pattern of FI performance were unaffected. Cyclohexane exposures of 500 or 2000 ppm had no detectable effects. No enduring effects of cyclohexane occurred up to 2 weeks after exposure. An independent set of rats, trained under nominally identical conditions, received various doses (i.p.) of d-amphetamine (AMPH) or chlorpromazine (CPZ) at 1–2 week intervals. Effective doses of AMPH decreased FR running rate, decreased FR post-reinforcement pause duration and increased FI rate of response. AMPH also decreased the FI index of curvature, indicating a change from an accelerating rate during the FI to a more constant rate. Effective doses of CPZ decreased FR rate, increased FR pause duration, decreased FI rate, and decreased FI index of curvature. Thus, schedule-controlled operant procedures that were sensitive to the effects of psychoactive drugs were able to identify only a minor and transient effect of the highest concentration (7000 ppm) of cyclohexane vapor on operant performance.

Effects of cyclohexane, an industrial solvent, on the yeast Saccharomyces cerevisiae and on isolated yeast mitochondria

Little information on the effects of cyclohexane at the cellular or subcellular level is available. In Saccharomyces cerevisiae, cyclohexane inhibited respiration and diverse energy-dependent processes. In mitochondria isolated from S. cerevisiae, oxygen uptake and ATP synthesis were inhibited, although ATPase activity was not affected. Cyclohexane effects were similar to those reported for beta-pinene and limonene, suggesting that the cyclohexane ring in these monoterpenes may be a determinant for their biological activities.

Infrared Detection of Specific Solvent Effects of Cyclohexane towards the Halogens

The study of molecular interactions in solution has long been complicated, hindered and even nullified1–2 by the problem of finding an ‘inert’ solvent which does not compete with one of the interac...

The Effect of Solvents on the γ-Ray Radiolysis of Methyl Acetate and Acetone

The effect of cyclohexane and benzene on the radiolysis of CH/sub 3/ COOCH/sub 3/, CH/sub 3/COOCD/sub 3/, and mixtures of CH/sub 3/COCH/sub 3/CD/sub 3/ COCD/sub 3/ was investigated at 17 deg . In the absence of scavengers, cyclohexane markedly reduces the yield of CO, whereas, in the presence of scavengers, it produces no effect. Benzene inhibits the decomposition of methyl acetate and acetone. Hydrogen is mostly formed in processes involving hot hydrogen atoms. The effect of the solvents on the yields of ethanes and some of the methanes indicates the impontance of cage and intercage recombinations and dispropontionations of the radicals in the gamma -ray track. The radiolysis of a CH/sub 3/COCH/sub 3/- CD/sub 3/COCD/sub 3/ mixture at -195 deg is discussed briefly. (auth)